Obstructive sleep apnea (OSA) is a medical condition in which a patient's upper airway is repeatedly partially or fully occluded during sleep. These repeated occlusions of the upper airway may cause sleep fragmentation, which in turn may result in sleep deprivation, daytime tiredness, and malaise. More serious instances of OSA may increase the patient's risk for stroke, cardiac arrhythmias, high blood pressure, and/or other disorders.
OSA may be characterized by the tendency of the soft tissues of the upper airway to collapse during sleep, thereby occluding the upper airway. More specifically, OSA is typically caused by the collapse of the patient's soft palate and/or by the collapse of the patient's tongue (e.g., onto the back of the pharynx), which in turn may obstruct normal breathing.
There are many treatments available for OSA including, for example: surgery, constant positive airway pressure (CPAP) machines, and the electrical stimulation of muscles associated with moving the tongue. Surgical techniques include tracheotomies, procedures to remove portions of a patient's tongue and/or soft palate, and other procedures that seek to prevent collapse of the tongue into the back of the pharynx. These surgical techniques are very invasive. CPAP machines seek to maintain upper airway patency by applying positive air pressure at the patient's nose and mouth. However, these machines are uncomfortable and may have low compliance rates.
Some electrical stimulation techniques seek to prevent collapse of the tongue into the back of the pharynx by causing the tongue to protrude forward (e.g., in an anterior direction) during sleep. For one example, U.S. Pat. No. 4,830,008 to Meer discloses an invasive technique in which electrodes are implanted into a patient at locations on or near nerves that stimulate the Genioglossus muscle to move the tongue forward (e.g., away from the back of the pharynx). For another example, U.S. Pat. No. 7,711,438 to Lattner discloses a non-invasive technique in which electrodes, mounted on an intraoral device, electrically stimulate the Genioglossus muscle to cause the tongue to move forward during respiratory inspiration. In addition, U.S. Pat. No. 8,359,108 to McCreery teaches an intraoral device that applies electrical stimulation to the Hypoglossal nerve to contract the Genioglossus muscle, which as mentioned above may prevent tongue collapse by moving the tongue forward during sleep.
Moving a patient's tongue forward during sleep may cause the patient to wake, which is not desirable. In addition, existing techniques for electrically stimulating the Hypoglossal nerve and/or the Genioglossus muscle may cause discomfort and/or pain, which is not desirable. Further, invasive techniques for electrically stimulating the Hypoglossal nerve and/or the Genioglossus muscle undesirably require surgery and introduce foreign matter into the patient's tissue, which is undesirable.
Thus, there is a need for a non-invasive treatment for OSA that does not disturb or wake-up the patient during use.